I was trying to use Logmein from my Suse 10 Linux laptop but the Java viewer kept crashing. Despite installing JVM 1.5 the plugin was still showing v1.4.2. I eventually found the plugin directory was /usr/lib/firefox/plugins and had to create a link from here to replace the Java v1.4.2 one.
The command I used was:
ln -s /usr/java/jre1.5.0_06/plugin/i386/ns7/libjavaplugin_oji.so /usr/lib/firefox/plugins/libjavaplugin_oji.so
The Mozilla plugin directory is /opt/mozilla/lib/plugins so adjust accordingly.
The Java verifier now shows both browsers using JRE 1.5.0_06 and Logmein works!